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• Various problems with software raid1 array built with Samsung 840 Pro SSDs

  - by Andy B

  I am bringing to ServerFault a problem that is tormenting me for 6+ months. I have a CentOS 6 (64bit) server with an md software raid-1 array with 2 x Samsung 840 Pro SSDs (512GB). Problems: Serious write speed problems: root [~]# time dd if=arch.tar.gz of=test4 bs=2M oflag=sync 146+1 records in 146+1 records out 307191761 bytes (307 MB) copied, 23.6788 s, 13.0 MB/s real 0m23.680s user 0m0.000s sys 0m0.932s When doing the above (or any other larger copy) the load spikes to unbelievable values (even over 100) going up from ~ 1. When doing the above I've also noticed very weird iostat results: Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 1589.50 0.00 54.00 0.00 13148.00 243.48 0.60 11.17 0.46 2.50 sdb 0.00 1627.50 0.00 16.50 0.00 9524.00 577.21 144.25 1439.33 60.61 100.00 md1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 md2 0.00 0.00 0.00 1602.00 0.00 12816.00 8.00 0.00 0.00 0.00 0.00 md0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 And it keeps it this way until it actually writes the file to the device (out from swap/cache/memory). The problem is that the second SSD in the array has svctm and await roughly 100 times larger than the second. For some reason the wear is different between the 2 members of the array root [~]# smartctl --attributes /dev/sda | grep -i wear 177 Wear_Leveling_Count 0x0013 094% 094 000 Pre-fail Always - 180 root [~]# smartctl --attributes /dev/sdb | grep -i wear 177 Wear_Leveling_Count 0x0013 070% 070 000 Pre-fail Always - 1005 The first SSD has a wear of 6% while the second SSD has a wear of 30%!! It's like the second SSD in the array works at least 5 times as hard as the first one as proven by the first iteration of iostat (the averages since reboot): Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 10.44 51.06 790.39 125.41 8803.98 1633.11 11.40 0.33 0.37 0.06 5.64 sdb 9.53 58.35 322.37 118.11 4835.59 1633.11 14.69 0.33 0.76 0.29 12.97 md1 0.00 0.00 1.88 1.33 15.07 10.68 8.00 0.00 0.00 0.00 0.00 md2 0.00 0.00 1109.02 173.12 10881.59 1620.39 9.75 0.00 0.00 0.00 0.00 md0 0.00 0.00 0.41 0.01 3.10 0.02 7.42 0.00 0.00 0.00 0.00 What I've tried: I've updated the firmware to DXM05B0Q (following reports of dramatic improvements for 840Ps after this update). I have looked for "hard resetting link" in dmesg to check for cable/backplane issues but nothing. I have checked the alignment and I believe they are aligned correctly (1MB boundary, listing below) I have checked /proc/mdstat and the array is Optimal (second listing below). root [~]# fdisk -ul /dev/sda Disk /dev/sda: 512.1 GB, 512110190592 bytes 255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00026d59 Device Boot Start End Blocks Id System /dev/sda1 2048 4196351 2097152 fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sda2 * 4196352 4605951 204800 fd Linux raid autodetect Partition 2 does not end on cylinder boundary. /dev/sda3 4605952 814106623 404750336 fd Linux raid autodetect root [~]# fdisk -ul /dev/sdb Disk /dev/sdb: 512.1 GB, 512110190592 bytes 255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0003dede Device Boot Start End Blocks Id System /dev/sdb1 2048 4196351 2097152 fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sdb2 * 4196352 4605951 204800 fd Linux raid autodetect Partition 2 does not end on cylinder boundary. /dev/sdb3 4605952 814106623 404750336 fd Linux raid autodetect /proc/mdstat root # cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb2[1] sda2[0] 204736 blocks super 1.0 [2/2] [UU] md2 : active raid1 sdb3[1] sda3[0] 404750144 blocks super 1.0 [2/2] [UU] md1 : active raid1 sdb1[1] sda1[0] 2096064 blocks super 1.1 [2/2] [UU] unused devices: Running a read test with hdparm root [~]# hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 664 MB in 3.00 seconds = 221.33 MB/sec root [~]# hdparm -t /dev/sdb /dev/sdb: Timing buffered disk reads: 288 MB in 3.01 seconds = 95.77 MB/sec But look what happens if I add --direct root [~]# hdparm --direct -t /dev/sda /dev/sda: Timing O_DIRECT disk reads: 788 MB in 3.01 seconds = 262.08 MB/sec root [~]# hdparm --direct -t /dev/sdb /dev/sdb: Timing O_DIRECT disk reads: 534 MB in 3.02 seconds = 176.90 MB/sec Both tests increase but /dev/sdb doubles while /dev/sda increases maybe 20%. I just don't know what to make of this. As suggested by Mr. Wagner I've done another read test with dd this time and it confirms the hdparm test: root [/home2]# dd if=/dev/sda of=/dev/null bs=1G count=10 10+0 records in 10+0 records out 10737418240 bytes (11 GB) copied, 38.0855 s, 282 MB/s root [/home2]# dd if=/dev/sdb of=/dev/null bs=1G count=10 10+0 records in 10+0 records out 10737418240 bytes (11 GB) copied, 115.24 s, 93.2 MB/s So sda is 3 times faster than sdb. Or maybe sdb is doing also something else besides what sda does. Is there some way to find out if sdb is doing more than what sda does? UPDATE Again, as suggested by Mr. Wagner, I have swapped the 2 SSDs. And as he thought it would happen, the problem moved from sdb to sda. So I guess I'll RMA one of the SSDs. I wonder if the cage might be problematic. What is wrong with this array? Please help!

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• Accessing a vector<vector<int>> as a flat array

  - by user1762276

  For this array: vector<vector<int> > v; v.push_back(vector<int>(0)); v.back().push_back(1); v.back().push_back(2); v.back().push_back(3); v.back().push_back(4); I can output {1, 2, 3, 4} easily enough: cout << v[0][0] << endl; cout << v[0][1] << endl; cout << v[0][2] << endl; cout << v[0][3] << endl; To access it as a flat array I can do this: int* z = (int*)&v[0].front(); cout << z[0] << endl; cout << z[1] << endl; cout << z[2] << endl; cout << z[3] << endl; Now, how do I access the multidimensional vector as a flat multidimensional array? I cannot use the same format as accessing a single-dimensional vector: // This does not work (outputs garbage) int** n = (int**)&v.front(); cout << n[0][0] << endl; cout << n[0][1] << endl; cout << n[0][2] << endl; cout << n[0][3] << endl; The workaround I've found is to do this: int** n = new int* [v.size()]; for (size_t i = 0; i < v.size(); i++) { n[i] = &v.at(i).front(); } cout << n[0][0] << endl; cout << n[0][1] << endl; cout << n[0][2] << endl; cout << n[0][3] << endl; Is there a way to access the entire multidimensional vector like a flat c-style array without having to dynamically allocate each dimension above the data before accessing it? Speed is not critical in the implementation and clarity for maintenance is paramount. A multidimensional vector is just fine for storing the data. However, I want to also expose the data as a flat c-style array in the SDK so that it can be easily accessible by other languages. This means that exposing the vectors as an STL object is a no go. The solution I came up with works fine for my needs as I only evaluate the array once at the very end of processing to "flatten" it. However, is there a better way to go about this? Or am I already doing it the best way I possibly can without re-implementing my own data structure (overkill since my flatten code is only a few lines). Thank you for your advice, friends!

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• [C#][XNA] Draw() 20,000 32 by 32 Textures or 1 Large Texture 20,000 Times

  - by Rudi

  The title may be confusing - sorry about that, it's a poor summary. Here's my dilemma. I'm programming in C# using the .NET Framework 4, and aiming to make a tile-based game with XNA. I have one large texture (256 pixels by 4096 pixels). Remember this is a tile-based game, so this texture is so massive only because it contains many tiles, which are each 32 pixels by 32 pixels. I think the experts will definitely know what a tile-based game is like. The orientation is orthogonal (like a chess board), not isometric. In the Game.Draw() method, I have two choices, one of which will be incredibly more efficient than the other. Choice/Method #1: Semi-Pseudocode: public void Draw() { // map tiles are drawn left-to-right, top-to-bottom for (int x = 0; x < mapWidth; x++) { for (int y = 0; y < mapHeight; y++) { SpriteBatch.Draw( MyLargeTexture, // One large 256 x 4096 texture new Rectangle(x, y, 32, 32), // Destination rectangle - ignore this, its ok new Rectangle(x, y, 32, 32), // Notice the source rectangle 'cuts out' 32 by 32 squares from the texture corresponding to the loop Color.White); // No tint - ignore this, its ok } } } Caption: So, effectively, the first method is referencing one large texture many many times, each time using a small rectangle of this large texture to draw the appropriate tile image. Choice/Method #2: Semi-Pseudocode: public void Draw() { // map tiles are drawn left-to-right, top-to-bottom for (int x = 0; x < mapWidth; x++) { for (int y = 0; y < mapHeight; y++) { Texture2D tileTexture = map.GetTileTexture(x, y); // Getting a small 32 by 32 texture (different each iteration of the loop) SpriteBatch.Draw( tileTexture, new Rectangle(x, y, 32, 32), // Destination rectangle - ignore this, its ok new Rectangle(0, 0, tileTexture.Width, tileTexture.Height), // Notice the source rectangle uses the entire texture, because the entire texture IS 32 by 32 Color.White); // No tint - ignore this, its ok } } } Caption: So, effectively, the second method is drawing many small textures many times. The Question: Which method and why? Personally, I would think it would be incredibly more efficient to use the first method. If you think about what that means for the tile array in a map (think of a large map with 2000 by 2000 tiles, let's say), each Tile object would only have to contain 2 integers, for the X and Y positions of the source rectangle in the one large texture - 8 bytes. If you use method #2, however, each Tile object in the tile array of the map would have to store a 32by32 Texture - an image - which has to allocate memory for the R G B A pixels 32 by 32 times - is that 4096 bytes per tile then? So, which method and why? First priority is speed, then memory-load, then efficiency or whatever you experts believe.

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• Confusion on C++ Python extensions. Things like getting C++ values for python values.

  - by Matthew Mitchell

  I'm wanted to convert some of my python code to C++ for speed but it's not as easy as simply making a C++ function and making a few function calls. I have no idea how to get a C++ integer from a python integer object. I have an integer which is an attribute of an object that I want to use. I also have integers which are inside a list in the object which I need to use. I wanted to test making a C++ extension with this function: def setup_framebuffer(surface,flip=False): #Create texture if not done already if surface.texture is None: create_texture(surface) #Render child to parent if surface.frame_buffer is None: surface.frame_buffer = glGenFramebuffersEXT(1) glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, c_uint(int(surface.frame_buffer))) glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, surface.texture, 0) glPushAttrib(GL_VIEWPORT_BIT) glViewport(0,0,surface._scale[0],surface._scale[1]) glMatrixMode(GL_PROJECTION) glLoadIdentity() #Load the projection matrix if flip: gluOrtho2D(0,surface._scale[0],surface._scale[1],0) else: gluOrtho2D(0,surface._scale[0],0,surface._scale[1]) That function calls create_texture, so I will have to pass that function to the C++ function which I will do with the third argument. This is what I have so far, while trying to follow information on the python documentation: #include <Python.h> #include <GL/gl.h> static PyMethodDef SpamMethods[] = { ... {"setup_framebuffer", setup_framebuffer, METH_VARARGS,"Loads a texture from a Surface object to the OpenGL framebuffer."}, ... {NULL, NULL, 0, NULL} /* Sentinel */ }; static PyObject * setup_framebuffer(PyObject *self, PyObject *args){ bool flip; PyObject *create_texture, *arg_list,*pyflip,*frame_buffer_id; if (!PyArg_ParseTuple(args, "OOO", &surface,&pyflip,&create_texture)){ return NULL; } if (PyObject_IsTrue(pyflip) == 1){ flip = true; }else{ flip = false; } Py_XINCREF(create_texture); //Create texture if not done already if(texture == NULL){ arglist = Py_BuildValue("(O)", surface) result = PyEval_CallObject(create_texture, arglist); Py_DECREF(arglist); if (result == NULL){ return NULL; } Py_DECREF(result); } Py_XDECREF(create_texture); //Render child to parent frame_buffer_id = PyObject_GetAttr(surface, Py_BuildValue("s","frame_buffer")) if(surface.frame_buffer == NULL){ glGenFramebuffersEXT(1,frame_buffer_id); } glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, surface.frame_buffer)); glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, surface.texture, 0); glPushAttrib(GL_VIEWPORT_BIT); glViewport(0,0,surface._scale[0],surface._scale[1]); glMatrixMode(GL_PROJECTION); glLoadIdentity(); //Load the projection matrix if (flip){ gluOrtho2D(0,surface._scale[0],surface._scale[1],0); }else{ gluOrtho2D(0,surface._scale[0],0,surface._scale[1]); } Py_INCREF(Py_None); return Py_None; } PyMODINIT_FUNC initcscalelib(void){ PyObject *module; module = Py_InitModule("cscalelib", Methods); if (m == NULL){ return; } } int main(int argc, char *argv[]){ /* Pass argv[0] to the Python interpreter */ Py_SetProgramName(argv[0]); /* Initialize the Python interpreter. Required. */ Py_Initialize(); /* Add a static module */ initscalelib(); }

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• extensible database design: automatic ALTER TABLE or serialize() field BLOB ?

  - by mario

  I want an adaptable database scheme. But still use a simple table data gateway in my application, where I just pass an $data[] array for storing. The basic columns are settled in the initial table scheme. There will however arise a couple of meta fields later (ca 10-20). I want some flexibility there and not adapt the database manually each time, or -worse- change the application logic just because of new fields. So now there are two options which seem workable yet not overkill. But I'm not sure about the scalability or database drawbacks. (1) Automatic ALTER TABLE. Whenever the $data array is to be saved, the keys are compared against the current database columns. New columns get defined before the $data is INSERTed into the table. Actually seems simple enough in test code: function save($data, $table="forum") { // columns if ($new_fields = array_diff(array_keys($data), known_fields($table))) { extend_schema($table, $new_fields, $data); } // save $columns = implode("`, `", array_keys($data)); $qm = str_repeat(",?", count(array_keys($data)) - 1); echo ("INSERT INTO `$table` (`$columns`) VALUES (?$qm);"); function known_fields($table) { return unserialize(@file_get_contents("db:$table")) ?: array("id"); function extend_schema($table, $new_fields, $data) { foreach ($new_fields as $field) { echo("ALTER TABLE `$table` ADD COLUMN `$field` VARCHAR;"); Since it is mostly meta information fields, adding them just as VARCHAR seems sufficient. Nobody will query by them anyway. So the database is really just used as storage here. However, while I might want to add a lot of new $data fields on the go, they will not always be populated. (2) serialize() fields into BLOB. Any new/extraneous meta fields could be opaque to the database. Simply sorting out the virtual fields from the real database columns is simple. And the meta fields can just be serialize()d into a blob/text field then: function ext_save($data, $table="forum") { $db_fields = array("id", "content", "flags", "ext"); // disjoin foreach (array_diff(array_keys($data),$db_fields) as $key) { $data["ext"][$key] = $data[$key]; unset($data[$key]); } $data["ext"] = serialize($data["ext"]); Unserializing and unpacking this 'ext' column on read queries is a minor overhead. The advantage is that there won't be any sparsely filled columns in the database, so I guess it's compacter and faster than the AUTO ALTER TABLE approach. Of course, this method prevents ever using one of the new fields in a WHERE or GROUP BY clause. But I think none of the possible meta fields (user_agent, author_ip, author_img, votes, hits, last_modified, ..) would/should ever be used there anyway. So I currently prefer the 'ext' blob approach, even if it's a one-way ticket. How are such columns called usually? (looking for examples/doc) Would you use XML serialization for (very theoretical) in-database queries? The adapting table scheme seems a "cleaner" interface, even if most columns might remain empty then. How does that impact speed? How many such sparse VARCHAR fields can MySQL/innodb stomach? But most importantly: Is there any standard implementation for this? A pseudo ORM with automatic ALTER TABLE tricks? Storing a simple column list seems workable, but something like pdo::getColumnMeta would be more robust.

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• jQuery , Trigger change event on newly created elements

  - by kwhohasamullet

  Hi Guys, I have a button in a form that when clicked adds another set of form fields, In these form fields there are 2 drop downs where the contents of the 2nd dropdown rely on what is selected in the first dropdown... What i want to do is when the new form field button is clicked for the new items to be added and then the change event to be triggered on the drop down that was created so what only that drop down changes and not all the drop downs with the same name currently in that form. THe first drop down is called product Category The code for the addFormField function is: function addFormField() { var id = document.getElementById("field_id").value; $("#products").append("<table width='600' cellpadding='5' cellspacing='0' class='Add_Products' id='row" + id + "'><td width='250' class='left'><label>Select Product Category</label></td><td class='right' ><label><select name='" + id + "' id='ProductCategory'><?php foreach($categories as $key=>$category){ echo "<option value=".$key.">".$category."</option>"; } ?></select></label></td></tr><tr><td width='250' class='left'><label>Select Product Template</label></td><td class='right' ><label><select name='data[QuoteItem][" + id + "][product_id]' id='QuoteItem" + id + "product_id' class='Product' title='" + id + "'></select></label></td></tr><tr ><td class='left'>Name</td><td class='right'><label><input name='data[QuoteItem][" + id + "][name]' type='text' id='QuoteItem" + id + "name' size='50' /></label></td></tr><tr ><td class='left'>Price (ex GST)</td><td class='right'><input type='text' name='data[QuoteItem][" + id + "][price]' id='QuoteItem" + id + "price' onchange='totalProductPrice();' class='quote-item-price' value='0' /></td></tr><tr><td class='left'>Description</td><td class='right'><label><textarea name='data[QuoteItem][" + id + "][description]' cols='38' rows='5' id='QuoteItem" + id + "description'></textarea></label></td></tr><tr><td><a href='#' onClick='removeFormField(\"#row" + id + "\"); return false;'>Remove</a></td></tr></table>"); $('#row' + id).highlightFade({ speed:1000 }); id = (id - 1) + 2; document.getElementById("field_id").value = id; } The code that detects change in ProductCategory dropdown and triggers the AJAX is below: $("select#ProductCategory").live('change', function(){ var url = base + "/quotes/productList/" + $(this).val() + ""; var id = $(this).attr('name'); $.getJSON(url,{id: $(this).val(), ajax: 'true'}, function(j){ var options = ''; options += '<option value="0">None</option>'; $.each(j, function(key, value){ options += '<option value="' + key + '">' + value + '</option>'; }) $("select#QuoteItem" + id + "product_id").html(options); }) }).trigger('change'); I have been trying all afternoon to work this out and the closest one i got to work applied the returned ajax values to all items. Currently using the live function people can add new fields and are able to use the drops down independant of each other dropdown but its only when the field is first added that i have trouble getting is populated Thanks in advance for any help

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• what persistence layer (xml or mysql) should i use for this xml data?

  - by fayer

  i wonder how i could store a xml structure in a persistence layer. cause the relational data looks like: <entity id="1000070"> <name>apple</name> <entities> <entity id="7002870"> <name>mac</name> <entities> <entity id="7002907"> <name>leopard</name> <entities> <entity id="7024080"> <name>safari</name> </entity> <entity id="7024701"> <name>finder</name> </entity> </entities> </entity> </entities> </entity> <entity id="7024080"> <name>iphone</name> <entities> <entity id="7024080"> <name>3g</name> </entity> <entity id="7024701"> <name>3gs</name> </entity> </entities> </entity> <entity id="7024080"> <name>ipad</name> </entity> </entities> </entity> as you can see, it has no static structure but a dynamical one. mac got 2 descendant levels while iphone got 1 and ipad got 0. i wonder how i could store this data the best way? what are my options. cause it seems impossible to store it in a mysql database due to this dynamical structure. is the only way to store it as a xml file then? is the speed of getting information (xpath/xquery/simplexml) from a xml file worse or greater than from mysql? what are the pros and cons? do i have other options? is storing information in xml files, suited for a lot of users accessing it at the same time? would be great with feedbacks!! thanks! EDIT: now i noticed that i could use something called xml database to store xml data. could someone shed a light on this issue? cause apparently its not as simple as just store data in a xml file?

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• Converting switch statements to more elegant solution.

  - by masfenix

  I have a 9 x 9 matrix. (think of suduko). 4 2 1 6 8 1 8 5 8 3 1 5 8 1 1 7 5 8 1 1 4 0 5 6 7 0 4 6 2 5 5 4 4 8 1 2 6 8 8 2 8 1 6 3 5 8 4 2 6 4 7 4 1 1 1 3 5 3 8 8 5 2 2 2 6 6 0 8 8 8 0 6 8 7 2 3 3 1 1 7 4 now I wanna be able to get a "quadrant". for example (according to my code) the quadrant 2 , 2 returns the following: 5 4 4 2 8 1 6 4 7 If you've noticed, this is the matrix from the very center of the 9 x 9. I've split everything up in to pairs of "3" if you know what i mean. the first "ROW" is from 0 - 3, the second from 3 - 6, the third for 6 - 9.. I hope this makes sense ( I am open to alternate ways to go about this) anyways, heres my code. I dont really like this way, even though it works. I do want speed though beccause i am making a suduko solver. //a quadrant returns the mini 3 x 3 //row 1 has three quads,"1", "2", 3" //row 2 has three quads "1", "2", "3" etc public int[,] GetQuadrant(int rnum, int qnum) { int[,] returnMatrix = new int[3, 3]; int colBegin, colEnd, rowBegin, rowEnd, row, column; //this is so we can keep track of the new matrix row = 0; column = 0; switch (qnum) { case 1: colBegin = 0; colEnd = 3; break; case 2: colBegin = 3; colEnd = 6; break; case 3: colBegin = 6; colEnd = 9; break; default: colBegin = 0; colEnd = 0; break; } switch (rnum) { case 1: rowBegin = 0; rowEnd = 3; break; case 2: rowBegin = 3; rowEnd = 6; break; case 3: rowBegin = 6; rowEnd = 9; break; default: rowBegin = 0; rowEnd = 0; break; } for (int i = rowBegin ; i < rowEnd; i++) { for (int j = colBegin; j < colEnd; j++) { returnMatrix[row, column] = _matrix[i, j]; column++; } column = 0; row++; } return returnMatrix; }

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• Game logic dynamically extendable architecture implementation patterns

  - by Vlad

  When coding games there are a lot of cases when you need to inject your logic into existing class dynamically and without making unnecessary dependencies. For an example I have a Rabbit which can be affected by freeze ability so it can't jump. It could be implemented like this: class Rabbit { public bool CanJump { get; set; } void Jump() { if (!CanJump) return; ... } } But If I have more than one ability that can prevent it from jumping? I can't just set one property because some circumstances can be activated simultanously. Another solution? class Rabbit { public bool Frozen { get; set; } public bool InWater { get; set; } bool CanJump { get { return !Frozen && !InWater; } } } Bad. The Rabbit class can't know all the circumstances it can run into. Who knows what else will game designer want to add: may be an ability that changes gravity on an area? May be make a stack of bool values for CanJump property? No, because abilities can be deactivated not in that order in which they were activated. I need a way to seperate ability logic that prevent the Rabbit from jumping from the Rabbit itself. One possible solution for this is making special checking event: class Rabbit { class CheckJumpEventArgs : EventArgs { public bool Veto { get; set; } } public event EventHandler<CheckJumpEvent> OnCheckJump; void Jump() { var args = new CheckJumpEventArgs(); if (OnCheckJump != null) OnCheckJump(this, args); if (!args.Veto) return; ... } } But it's a lot of code! A real Rabbit class would have a lot of properties like this (health and speed attributes, etc). I'm thinking of borrowing something from MVVM pattern where you have all the properties and methods of an object implemented in a way where they can be easily extended from outside. Then I want to use it like this: class FreezeAbility { void ActivateAbility() { _rabbit.CanJump.Push(ReturnFalse); } void DeactivateAbility() { _rabbit.CanJump.Remove(ReturnFalse); } // should be implemented as instance member // so it can be "unsubscribed" bool ReturnFalse(bool previousValue) { return false; } } Is this approach good? What also should I consider? What are other suitable options and patterns? Any ready to use solutions? UPDATE The question is not about how to add different behaviors to an object dynamically but how its (or its behavior) implementation can be extended with external logic. I don't need to add a different behavior but I need a way to modify an exitsing one and I also need a possibiliity to undo changes.

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• What version-control system is most trivial to set up and use for toy projects?

  - by Norman Ramsey

  I teach the third required intro course in a CS department. One of my homework assignments asks students to speed up code they have written for a previous assignment. Factor-of-ten speedups are routine; factors of 100 or 1000 are not unheard of. (For a factor of 1000 speedup you have to have made rookie mistakes with malloc().) Programs are improved by a sequence is small changes. I ask students to record and describe each change and the resulting improvement. While you're improving a program it is also possible to break it. Wouldn't it be nice to back out? You can see where I'm going with this: my students would benefit enormously from version control. But there are some caveats: Our computing environment is locked down. Anything that depends on a central repository is suspect. Our students are incredibly overloaded. Not just classes but jobs, sports, music, you name it. For them to use a new tool it has to be incredibly easy and have obvious benefits. Our students do most work in pairs. Getting bits back and forth between accounts is problematic. Could this problem also be solved by distributed version control? Complexity is the enemy. I know setting up a CVS repository is too baffling---I myself still have trouble because I only do it once a year. I'm told SVN is even harder. Here are my comments on existing systems: I think central version control (CVS or SVN) is ruled out because our students don't have the administrative privileges needed to make a repository that they can share with one other student. (We are stuck with Unix file permissions.) Also, setup on CVS or SVN is too hard. darcs is way easy to set up, but it's not obvious how you share things. darcs send (to send patches by email) seems promising but it's not clear how to set it up. The introductory documentation for git is not for beginners. Like CVS setup, it's something I myself have trouble with. I'm soliciting suggestions for what source-control to use with beginning students. I suspect we can find resources to put a thin veneer over an existing system and to simplify existing documentation. We probably don't have resources to write new documentation. So, what's really easy to setup, commit, revert, and share changes with a partner but does not have to be easy to merge or to work at scale? A key constraint is that programming pairs have to be able to share work with each other and only each other, and pairs change every week. Our infrastructure is Linux, Solaris, and Windows with a netapp filer. I doubt my IT staff wants to create a Unix group for each pair of students. Is there an easier solution I've overlooked? (Thanks for the accepted answer, which beats the others on account of its excellent reference to Git Magic as well as the helpful comments.)

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• Javascript and Twitter API rate limitation? (Changing variable values in a loop)

  - by Pablo

  Hello, I have adapted an script from an example of http://github.com/remy/twitterlib. It´s a script that makes one query each 10 seconds to my Twitter timeline, to get only the messages that begin with a musical notation. It´s already working, but I don´t know it is the better way to do this... The Twitter API has a rate limit of 150 IP access per hour (queries from the same user). At this time, my Twitter API is blocked at 25 minutes because the 10 seconds frecuency between posts. If I set up a frecuency of 25 seconds between post, I am below the rate limit per hour, but the first 10 posts are shown so slowly. I think this way I can guarantee to be below the Twitter API rate limit and show the first 10 posts at normal speed: For the first 10 posts, I would like to set a frecuency of 5 seconds between queries. For the rest of the posts, I would like to set a frecuency of 25 seconds between queries. I think if making somewhere in the code a loop with the previous sentences, setting the "frecuency" value from 5000 to 25000 after the 10th query (or after 50 seconds, it´s the same), that´s it... Can you help me on modify this code below to make it work? Thank you in advance. var Queue = function (delay, callback) { var q = [], timer = null, processed = {}, empty = null, ignoreRT = twitterlib.filter.format('-"RT @"'); function process() { var item = null; if (q.length) { callback(q.shift()); } else { this.stop(); setTimeout(empty, 5000); } return this; } return { push: function (item) { var green = [], i; if (!(item instanceof Array)) { item = [item]; } if (timer == null && q.length == 0) { this.start(); } for (i = 0; i < item.length; i++) { if (!processed[item[i].id] && twitterlib.filter.match(item[i], ignoreRT)) { processed[item[i].id] = true; q.push(item[i]); } } q = q.sort(function (a, b) { return a.id > b.id; }); return this; }, start: function () { if (timer == null) { timer = setInterval(process, delay); } return this; }, stop: function () { clearInterval(timer); timer = null; return this; }, empty: function (fn) { empty = fn; return this; }, q: q, next: process }; }; $.extend($.expr[':'], { below: function (a, i, m) { var y = m[3]; return $(a).offset().top y; } }); function renderTweet(data) { var html = ''; html += ''; html += twitterlib.ify.clean(data.text); html += ''; since_id = data.id; return html; } function passToQueue(data) { if (data.length) { twitterQueue.push(data.reverse()); } } var frecuency = 10000; // The lapse between each new Queue var since_id = 1; var run = function () { twitterlib .timeline('twitteruser', { filter : "'?'", limit: 10 }, passToQueue) }; var twitterQueue = new Queue(frecuency, function (item) { var tweet = $(renderTweet(item)); var tweetClone = tweet.clone().hide().css({ visibility: 'hidden' }).prependTo('#tweets').slideDown(1000); tweet.css({ top: -200, position: 'absolute' }).prependTo('#tweets').animate({ top: 0 }, 1000, function () { tweetClone.css({ visibility: 'visible' }); $(this).remove(); }); $('#tweets p:below(' + window.innerHeight + ')').remove(); }).empty(run); run();

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• Help with optimizing C# function via C and/or Assembly

  - by MusiGenesis

  I have this C# method which I'm trying to optimize: // assume arrays are same dimensions private void DoSomething(int[] bigArray1, int[] bigArray2) { int data1; byte A1; byte B1; byte C1; byte D1; int data2; byte A2; byte B2; byte C2; byte D2; for (int i = 0; i < bigArray1.Length; i++) { data1 = bigArray1[i]; data2 = bigArray2[i]; A1 = (byte)(data1 >> 0); B1 = (byte)(data1 >> 8); C1 = (byte)(data1 >> 16); D1 = (byte)(data1 >> 24); A2 = (byte)(data2 >> 0); B2 = (byte)(data2 >> 8); C2 = (byte)(data2 >> 16); D2 = (byte)(data2 >> 24); A1 = A1 > A2 ? A1 : A2; B1 = B1 > B2 ? B1 : B2; C1 = C1 > C2 ? C1 : C2; D1 = D1 > D2 ? D1 : D2; bigArray1[i] = (A1 << 0) | (B1 << 8) | (C1 << 16) | (D1 << 24); } } The function basically compares two int arrays. For each pair of matching elements, the method compares each individual byte value and takes the larger of the two. The element in the first array is then assigned a new int value constructed from the 4 largest byte values (irrespective of source). I think I have optimized this method as much as possible in C# (probably I haven't, of course - suggestions on that score are welcome as well). My question is, is it worth it for me to move this method to an unmanaged C DLL? Would the resulting method execute faster (and how much faster), taking into account the overhead of marshalling my managed int arrays so they can be passed to the method? If doing this would get me, say, a 10% speed improvement, then it would not be worth my time for sure. If it was 2 or 3 times faster, then I would probably have to do it. Note: please, no "premature optimization" comments, thanks in advance. This is simply "optimization".

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• Why is my program getting slower and slower ?

  - by RedWolf

  I'm using the program to send data from database to the Excel file . It works fine at the beginning and then becomes more and more slowly,finally it run out of the memory and the following error ocurrs: "java.lang.OutOfMemoryError: Java heap space...". The problem can be resolved by adding the jvm heap sapce.But the question is that it spends too much time to run out the program. After several minutes,it finished a loop with 4 seconds which can be finished with 0.5 seconds at the beginning . I can't found a solution to make it always run in a certain speed. Is it my code problem? Any clues on this? Here is the code: public void addAnswerRow(List<FinalUsers> finalUsersList,WritableWorkbook book){ if (finalUsersList.size() >0 ) { try { WritableSheet sheet = book.createSheet("Answer", 0); int colCount = 0; sheet.addCell(new Label(colCount++,0,"Number")); sheet.addCell(new Label(colCount++,0,"SchoolNumber")); sheet.addCell(new Label(colCount++,0,"District")); sheet.addCell(new Label(colCount++,0,"SchoolName")); sheet.setColumnView(1, 15); sheet.setColumnView(3, 25); List<Elements> elementsList = this.elementsManager.getObjectElementsByEduTypeAndQuestionnaireType(finalUsersList.get(0).getEducationType().getId(), this.getQuestionnaireByFinalUsersType(finalUsersList.get(0).getFinalUsersType().getId())); Collections.sort(elementsList, new Comparator<Elements>(){ public int compare(Elements o1, Elements o2) { for(int i=0; i< ( o1.getItemNO().length()>o2.getItemNO().length()? o2.getItemNO().length(): o1.getItemNO().length());i++){ if (CommonFun.isNumberic(o1.getItemNO().substring(0, o1.getItemNO().length()>3? 4: o1.getItemNO().length()-1)) && !CommonFun.isNumberic(o2.getItemNO().substring(0, o2.getItemNO().length()>3? 4: o2.getItemNO().length()-1))){ return 1; } if (!CommonFun.isNumberic(o1.getItemNO().substring(0, o1.getItemNO().length()>3? 4: o1.getItemNO().length()-1)) && CommonFun.isNumberic(o2.getItemNO().substring(0,o2.getItemNO().length()>3? 4:o2.getItemNO().length()-1))){ return -1; } if ( o1.getItemNO().charAt(i)!=o2.getItemNO().charAt(i) ){ return o1.getItemNO().charAt(i)-o2.getItemNO().charAt(i); } } return o1.getItemNO().length()> o2.getItemNO().length()? 1:-1; }}); for (Elements elements : elementsList){ sheet.addCell(new Label(colCount++,0,this.getTitlePre(finalUsersList.get(0).getFinalUsersType().getId(), finalUsersList.get(0).getEducationType().getId())+elements.getItemNO()+elements.getItem().getStem())); } int sheetRowCount =1; int sheetColCount =0; for(FinalUsers finalUsers : finalUsersList){ sheetColCount =0; sheet.addCell(new Label(sheetColCount++,sheetRowCount,String.valueOf(sheetRowCount))); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getSchoolNumber())); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getDistrict().getDistrictNumber().toString().trim())); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getName())); List<AnswerLog> answerLogList = this.answerLogManager.getAnswerLogByFinalUsers(finalUsers.getId()); Map<String,String> answerMap = new HashMap<String,String>(); for(AnswerLog answerLog :answerLogList ){ if (answerLog.getOptionsId() != null) { answerMap.put(answerLog.getElement().getItemNO(), this.getOptionsAnswer(answerLog.getOptionsId())); }else if (answerLog.getBlanks()!= null){ answerMap.put(answerLog.getElement().getItemNO(), answerLog.getBlanks()); }else{ answerMap.put(answerLog.getElement().getItemNO(), answerLog.getSubjectiveItemContent()); } } for (Elements elements : elementsList){ sheet.addCell(new Label(sheetColCount++,sheetRowCount,null==answerMap.get(elements.getItemNO())?"0":answerMap.get(elements.getItemNO()))); } sheetRowCount++; } book.write(); book.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (RowsExceededException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (WriteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

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• How to optimize this javascript code?

  - by Andrija

  I have a jsp which uses a lot of javascript and it's just not fast enough. I would like to optimize it so first, here's a part of the code: In the jsp I have the initialization: window.onload = function () { formCollection.pageSize.value = "<%= pagingSize%>"; elemCollection = iDom3.Table.all["spis"].XML.DOM; <% if (resultList != null) { %> elementsNumber = <%= resultList.size() %>; <%} else { %> elementsNumber = 0; <% } %> contextPath = "<%= request.getContextPath() %>"; } In my js file I have two types of js functions: // gets the first element and sets it's value to all the other; //the selectSingleNode function is used because I use XSLT transformation //to generate the table _setTehJed = function(){ var resultId = formCollection.elements["idTehJedinice_spis_1"].value; var resultText = formCollection.elements["tehnicka_spis_1"].value; if (resultId != ""){ var counter = 1; while (counter<elementsNumber){ counter++; if(formCollection.elements["idTehJedinice_spis_"+counter] != null){ formCollection.elements["idTehJedinice_spis_"+counter].value=resultId; formCollection.elements["tehnicka_spis_"+counter].value=resultText; } var node=elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'tehnicka']/title"); node.text=resultText; var node2=elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'idTehJedinice']/title"); node2.text=resultId; } } } // sets the elements checkbox to checked or unchecked _SelectCheckRokCuvanja = { all : [], Item : function (oItem, sId) { this.all["spis_"+sId] = oItem.value; if (oItem.checked) { elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "true"); }else{ elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "false"); } } } I've used these tips: http://blogs.msdn.com/b/ie/archive/2006/08/28/728654.aspx http://code.google.com/speed/articles/optimizing-javascript.html but I still think something could be done like defining the functions like this: In the jsp: window.onload = function () { iDom3.DigitalnaArhivaPrihvat.formCollection=document.forms["controller"]; iDom3.DigitalnaArhivaPrihvat.formCollection.pageSize.value = "<%= pagingSize%>"; iDom3.DigitalnaArhivaPrihvat.elemCollection = iDom3.Table.all["spis"].XML.DOM; <% if (resultList != null) { %> iDom3.DigitalnaArhivaPrihvat.elementsNumber = <%= resultList.size() %> <%} else { %> iDom3.DigitalnaArhivaPrihvat.elementsNumber = 0; <% } %> } in the js: iDom3.DigitalnaArhivaPrihvat = { formCollection:null, elemCollection:null, elementsNumber:null, _setTehJed : function(){ var resultId = this.formCollection.elements.idTehJedinice_spis_1.value; var resultText = this.formCollection.elements.tehnicka_spis_1.value; if (resultId != ""){ var counter = 1; while (counter<this.elementsNumber){ counter++; if(this.formCollection.elements["idTehJedinice_spis_"+counter] !== null){ this.formCollection.elements["idTehJedinice_spis_"+counter].value=resultId; this.formCollection.elements["tehnicka_spis_"+counter].value=resultText; } var node=this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'tehnicka']/title"); node.text=resultText; var node2=this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'idTehJedinice']/title"); node2.text=resultId; } } }, _SelectCheckRokCuvanja = { all : [], Item : function (oItem, sId) { this.all["spis_"+sId] = oItem.value; if (oItem.checked) { this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "true"); }else{ this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "false"); } } } but the problem is scoping (if I do it like this, the second function does not execute properly). Any suggestions?

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• C# slowdown while creating a bitmap - calculating distances from a large List of places for each pixel

  - by user576849

  I'm creating a graphic of the glow of lights above a geographic location based upon Walkers Law: Skyglow=0.01*Population*DistanceFromCenter^-2.5 I have a CSV file of places with 66,000 records using 5 fields (id,name,population,latitude,longitude), parsed on the FormLoad event and stored it in: List<string[]> placeDataList Then I set up nested loops to fill in a bitmap using SetPixel. For each pixel on the bitmap, which represents a coordinate on a map (latitude and longitude), the program loops through placeDataList – calculating the distance from that coordinate (pixel) to each place record. The distance (along with population) is used in a calculation to find how much cumulative sky glow is contributed to the coordinate from each place record. So, for every pixel, 66,000 distance calculations must be made. The problem is, this is predictably EXTREMELY slow – on the order of one line of pixels per 30 seconds or so on a 320 pixel wide image. This is unrelated to SetPixel, which I know is also slow, because the speed is similarly slow when adding the distance calculation results to an array. I don’t actually need to test all 66,000 records for every pixel, only the records within 150 miles (i.e. no skyglow is contributed to a coordinate from a small town 3000 miles away). But to find which records are within 150 miles of my coordinate I would still need to loop through all the records for each pixel. I can't use a smaller number of records because all 66,000 places contribute to skyglow for SOME coordinate in my map as it loops. This seems like a Catch-22, so I know there must be a better method out there. Like I mentioned, the slowdown is related to how many calculations I’m making per pixel, not anything to do with the bitmap. Any suggestions? private void fillPixels(int width) { Color pixelColor; int pixel_w = width; int pixel_h = (int)Math.Floor((width * 0.424088664)); Bitmap bmp = new Bitmap(pixel_w, pixel_h); for (int i = 0; i < pixel_h; i++) for (int j = 0; j < pixel_w; j++) { pixelColor = getPixelColor(i, j); bmp.SetPixel(j, i, pixelColor); } bmp.Save("Nightfall", System.Drawing.Imaging.ImageFormat.Jpeg); pictureBox1.Image = bmp; MessageBox.Show("Done"); } private Color getPixelColor(int height, int width) { int c; double glow,d,cityLat,cityLon,cityPop; double testLat, testLon; int size_h = (int)Math.Floor((size_w * 0.424088664)); ; testLat = (height * (24.443136 / size_h)) + 24.548874; testLon = (width * (57.636853 / size_w)) -124.640767; glow = 0; for (int i = 0; i < placeDataList.Count; i++) { cityPop=Convert.ToDouble(placeDataList[i][2]); cityLat=Convert.ToDouble(placeDataList[i][3]); cityLon=Convert.ToDouble(placeDataList[i][4]); d = distance(testLat, testLon, cityLat, cityLon,"M"); if(d<150) glow = glow+(0.01 * cityPop * Math.Pow(d, -2.5)); } if (glow >= 1) glow=1; c = (int)Math.Ceiling(glow * 255); return Color.FromArgb(c, c, c); }

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• Is this a SEO SAFE anchor link

  - by Mayhem

  so... Is this a safe way to use internal links on your site.. By doing this i have the index page generating the usual php content section and handing it to the div element. THE MAIN QUESTION: Will google still index the pages using this method? Common sense tells me it does.. But just double checking and leaving this here as a base example as well if it is. As in. EXAMPLE ONLY PEOPLE The Server Side if (isset($_REQUEST['page'])) {$pageID=$_REQUEST['page'];} else {$pageID="home";} if (isset($_REQUEST['pageMode']) && $_REQUEST['pageMode']=="js") { require "content/".$pageID.".php"; exit; } // ELSE - REST OF WEBSITE WILL BE GENERATED USING THE page VARIABLE The Links <a class='btnMenu' href='?page=home'>Home Page</a> <a class='btnMenu' href='?page=about'>About</a> <a class='btnMenu' href='?page=Services'>Services</a> <a class='btnMenu' href='?page=contact'>Contact</a> The Javascript $(function() { $(".btnMenu").click(function(){return doNav(this);}); }); function doNav(objCaller) { var sPage = $(objCaller).attr("href").substring(6,255); $.get("index.php", { page: sPage, pageMode: 'js'}, function(data) { ("#siteContent").html(data).scrollTop(0); }); return false; } Forgive me if there are any errors, as just copied and pasted from my script then removed a bunch of junk to simplify it as still prototyping/white boarding the project its in. So yes it does look a little nasty at the moment. REASONS WHY: The main reason is bandwidth and speed, This will allow other scripts to run and control the site/application a little better and yes it will need to be locked down with some coding. -- FURTHER EXAMPLE-- INSERT PHP AT TOP <?php // PHP CODE HERE ?> <html> <head> <link rel="stylesheet" type="text/css" href="style.css" /> <script type="text/javascript" src="jquery.js"></script> <script type="text/javascript" src="scripts.js"></script> </head> <body> <div class='siteBody'> <div class='siteHeader'> <?php foreach ($pageList as $key => $value) { if ($pageID == $key) {$btnClass="btnMenuSel";} else {$btnClass="btnMenu";} echo "<a class='$btnClass' href='?page=".$key."'>".$pageList[$key]."</a>"; } ?> </div><div id="siteContent" style='margin-top:10px;'> <?php require "content/".$pageID.".php"; ?> </div><div class='siteFooter'> </div> </div> </body> </html>

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• Why would Linux VM in vSphere ESXi 5.5 show dramatically increased disk i/o latency?

  - by mhucka

  I'm stumped and I hope someone else will recognize the symptoms of this problem. Hardware: new Dell T110 II, dual-core Pentium G860 2.9 GHz, onboard SATA controller, one new 500 GB 7200 RPM cabled hard drive inside the box, other drives inside but not mounted yet. No RAID. Software: fresh CentOS 6.5 virtual machine under VMware ESXi 5.5.0 (build 174 + vSphere Client). 2.5 GB RAM allocated. The disk is how CentOS offered to set it up, namely as a volume inside an LVM Volume Group, except that I skipped having a separate /home and simply have / and /boot. CentOS is patched up, ESXi patched up, latest VMware tools installed in the VM. No users on the system, no services running, no files on the disk but the OS installation. I'm interacting with the VM via the VM virtual console in vSphere Client. Before going further, I wanted to check that I configured things more or less reasonably. I ran the following command as root in a shell on the VM: for i in 1 2 3 4 5 6 7 8 9 10; do dd if=/dev/zero of=/test.img bs=8k count=256k conv=fdatasync done I.e., just repeat the dd command 10 times, which results in printing the transfer rate each time. The results are disturbing. It starts off well: 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 20.451 s, 105 MB/s 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 20.4202 s, 105 MB/s ... but after 7-8 of these, it then prints 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GG) copied, 82.9779 s, 25.9 MB/s 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 84.0396 s, 25.6 MB/s 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 103.42 s, 20.8 MB/s If I wait a significant amount of time, say 30-45 minutes, and run it again, it again goes back to 105 MB/s, and after several rounds (sometimes a few, sometimes 10+), it drops to ~20-25 MB/s again. Plotting the disk latency in vSphere's interface, it shows periods of high disk latency hitting 1.2-1.5 seconds during the times that dd reports the low throughput. (And yes, things get pretty unresponsive while that's happening.) What could be causing this? I'm comfortable that it is not due to the disk failing, because I also had configured two other disks as an additional volume in the same system. At first I thought I did something wrong with that volume, but after commenting the volume out from /etc/fstab and rebooting, and trying the tests on / as shown above, it became clear that the problem is elsewhere. It is probably an ESXi configuration problem, but I'm not very experienced with ESXi. It's probably something stupid, but after trying to figure this out for many hours over multiple days, I can't find the problem, so I hope someone can point me in the right direction. (P.S.: yes, I know this hardware combo won't win any speed awards as a server, and I have reasons for using this low-end hardware and running a single VM, but I think that's besides the point for this question [unless it's actually a hardware problem].) ADDENDUM #1: Reading other answers such as this one made me try adding oflag=direct to dd. However, it makes no difference in the pattern of results: initially the numbers are higher for many rounds, then they drop to 20-25 MB/s. (The initial absolute numbers are in the 50 MB/s range.) ADDENDUM #2: Adding sync ; echo 3 > /proc/sys/vm/drop_caches into the loop does not make a difference at all. ADDENDUM #3: To take out further variables, I now run dd such that the file it creates is larger than the amount of RAM on the system. The new command is dd if=/dev/zero of=/test.img bs=16k count=256k conv=fdatasync oflag=direct. Initial throughput numbers with this version of the command are ~50 MB/s. They drop to 20-25 MB/s when things go south. ADDENDUM #4: Here is the output of iostat -d -m -x 1 running in another terminal window while performance is "good" and then again when it's "bad". (While this is going on, I'm running dd if=/dev/zero of=/test.img bs=16k count=256k conv=fdatasync oflag=direct.) First, when things are "good", it shows this: When things go "bad", iostat -d -m -x 1 shows this:

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• HTML 5 <video> tag vs Flash video. What are the pros and cons?

  - by Vilx-

  Seems like the new <video> tag is all the hype these days, especially since Firefox now supports it. News of this are popping up in blogs all over the place, and everyone seems to be excited. But what about? As much as I searched I could not find anything that would make it better than the good old Flash video. In fact, I see only problems with it: It will still be some time before all the browsers start supporting it, and much more time before most people upgrade; Flash is available already and everyone has it; You can couple Flash with whatever fancy UI you want for controlling the playback. I gather that the tag will be controllable as well (via JavaScript probably), but will it be able to go fullscreen? The only two pros for a <video> tag that I can see are: It is more "semantic" - which probably holds no importance to a whole lot of people, including me; It is not dependent on a single commercial 3rd party entity (Adobe) - which I also don't see as a compelling reason to switch, because free players and video converters are already available, and Adobe is not hindering the whole process in any way (it's not in their interests even). So... what's the big deal? Added: OK, so there is one more Pro... maybe. Support for mobile devices. Hard to say though. A number of thoughts race through my head about the subject: How many mobile devices are actually able to decode video at a decent speed anyway, Flash or otherwise? How long until mainstream mobile devices get the <video> support? Even if it is available through updates, how many people actually do that? How many people watch videos on web pages on their mobile phones at all? As for the semantics part - I understand that search engines might be able to detect videos better now, but... what will they do with them anyway? OK, so they know that there is a video in the page. And? They can't index a video! I'd like some more arguments here. Added: Just thought of another Cons. This opens up a whole new area of cross-browser incompatibility. HTML and CSS is quite messy already in this aspect. Flash at least is the same everywhere. But it's enough for at least one major browser vendor to decide against the <video> tag (can anyone say "Internet Explorer"?) and we have a nice new area of hell to explore. Added: A Pro just came in. More competition = more innovation. That's true. Giving Adobe more competition will probably force them to improve Flash in areas it has been lacking so far. Linux seems to be a weak spot for it, cited by many.

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• Normalizing a table

  - by Alex

  I have a legacy table, which I can't change. The values in it can be modified from legacy application (application also can't be changed). Due to a lot of access to the table from new application (new requirement), I'd like to create a temporary table, which would hopefully speed up the queries. The actual requirement, is to calculate number of business days from X to Y. For example, give me all business days from Jan 1'st 2001 until Dec 24'th 2004. The table is used to mark which days are off, as different companies may have different days off - it isn't just Saturday + Sunday) The temporary table would be created from a .NET program, each time user enters the screen for this query (user may run query multiple times, with different values, table is created once), so I'd like it to be as fast as possible. Approach below runs in under a second, but I only tested it with a small dataset, and still it takes probably close to half a second, which isn't great for UI - even though it's just the overhead for first query. The legacy table looks like this: CREATE TABLE [business_days]( [country_code] [char](3) , [state_code] [varchar](4) , [calendar_year] [int] , [calendar_month] [varchar](31) , [calendar_month2] [varchar](31) , [calendar_month3] [varchar](31) , [calendar_month4] [varchar](31) , [calendar_month5] [varchar](31) , [calendar_month6] [varchar](31) , [calendar_month7] [varchar](31) , [calendar_month8] [varchar](31) , [calendar_month9] [varchar](31) , [calendar_month10] [varchar](31) , [calendar_month11] [varchar](31) , [calendar_month12] [varchar](31) , misc. ) Each month has 31 characters, and any day off (Saturday + Sunday + holiday) is marked with X. Each half day is marked with an 'H'. For example, if a month starts on a Thursday, than it will look like (Thursday+Friday workdays, Saturday+Sunday marked with X): ' XX XX ..' I'd like the new table to look like so: create table #Temp (country varchar(3), state varchar(4), date datetime, hours int) And I'd like to only have rows for days which are off (marked with X or H from previous query) What I ended up doing, so far is this: Create a temporary-intermediate table, that looks like this: create table #Temp_2 (country_code varchar(3), state_code varchar(4), calendar_year int, calendar_month varchar(31), month_code int) To populate it, I have a union which basically unions calendar_month, calendar_month2, calendar_month3, etc. Than I have a loop which loops through all the rows in #Temp_2, after each row is processed, it is removed from #Temp_2. To process the row there is a loop from 1 to 31, and substring(calendar_month, counter, 1) is checked for either X or H, in which case there is an insert into #Temp table. [edit added code] Declare @country_code char(3) Declare @state_code varchar(4) Declare @calendar_year int Declare @calendar_month varchar(31) Declare @month_code int Declare @calendar_date datetime Declare @day_code int WHILE EXISTS(SELECT * From #Temp_2) -- where processed = 0) BEGIN Select Top 1 @country_code = t2.country_code, @state_code = t2.state_code, @calendar_year = t2.calendar_year, @calendar_month = t2.calendar_month, @month_code = t2.month_code From #Temp_2 t2 -- where processed = 0 set @day_code = 1 while @day_code <= 31 begin if substring(@calendar_month, @day_code, 1) = 'X' begin set @calendar_date = convert(datetime, (cast(@month_code as varchar) + '/' + cast(@day_code as varchar) + '/' + cast(@calendar_year as varchar))) insert into #Temp (country, state, date, hours) values (@country_code, @state_code, @calendar_date, 8) end if substring(@calendar_month, @day_code, 1) = 'H' begin set @calendar_date = convert(datetime, (cast(@month_code as varchar) + '/' + cast(@day_code as varchar) + '/' + cast(@calendar_year as varchar))) insert into #Temp (country, state, date, hours) values (@country_code, @state_code, @calendar_date, 4) end set @day_code = @day_code + 1 end delete from #Temp_2 where @country_code = country_code AND @state_code = state_code AND @calendar_year = calendar_year AND @calendar_month = calendar_month AND @month_code = month_code --update #Temp_2 set processed = 1 where @country_code = country_code AND @state_code = state_code AND @calendar_year = calendar_year AND @calendar_month = calendar_month AND @month_code = month_code END I am not an expert in SQL, so I'd like to get some input on my approach, and maybe even a much better approach suggestion. After having the temp table, I'm planning to do (dates would be coming from a table): select cast(convert(datetime, ('01/31/2012'), 101) -convert(datetime, ('01/17/2012'), 101) as int) - ((select sum(hours) from #Temp where date between convert(datetime, ('01/17/2012'), 101) and convert(datetime, ('01/31/2012'), 101)) / 8) Besides the solution of normalizing the table, the other solution I implemented for now, is a function which does all this logic of getting the business days by scanning the current table. It runs pretty fast, but I'm hesitant to call a function, if I can instead add a simpler query to get result. (I'm currently trying this on MSSQL, but I would need to do same for Sybase ASE and Oracle)

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• Accessing a broken mdadm raid

  - by CarstenCarsten

  Hi! I used a western digital mybookworld (SOHO NAS storage using Linux) as backup for my Linux box. Suddenly, the mybookworld does not boot up any more. So I opened the box, removed the hard disk and put the hard disk into an external USB HDD case, and connected it to my Linux box. [ 530.640301] usb 2-1: new high speed USB device using ehci_hcd and address 3 [ 530.797630] scsi7 : usb-storage 2-1:1.0 [ 531.794844] scsi 7:0:0:0: Direct-Access WDC WD75 00AAKS-00RBA0 PQ: 0 ANSI: 2 [ 531.796490] sd 7:0:0:0: Attached scsi generic sg3 type 0 [ 531.797966] sd 7:0:0:0: [sdc] 1465149168 512-byte logical blocks: (750 GB/698 GiB) [ 531.800317] sd 7:0:0:0: [sdc] Write Protect is off [ 531.800327] sd 7:0:0:0: [sdc] Mode Sense: 38 00 00 00 [ 531.800333] sd 7:0:0:0: [sdc] Assuming drive cache: write through [ 531.803821] sd 7:0:0:0: [sdc] Assuming drive cache: write through [ 531.803836] sdc: sdc1 sdc2 sdc3 sdc4 [ 531.815831] sd 7:0:0:0: [sdc] Assuming drive cache: write through [ 531.815842] sd 7:0:0:0: [sdc] Attached SCSI disk The dmesg output looks normal, but I was wondering why the hardisk was not mounted at all. And why there are 4 different partitions on it. fdisk showed the following: root@ubuntu:/home/ubuntu# fdisk /dev/sdc WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u'). Command (m for help): p Disk /dev/sdc: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00007c00 Device Boot Start End Blocks Id System /dev/sdc1 4 369 2939895 fd Linux raid autodetect /dev/sdc2 370 382 104422+ fd Linux raid autodetect /dev/sdc3 383 505 987997+ fd Linux raid autodetect /dev/sdc4 506 91201 728515620 fd Linux raid autodetect Oh no! Everything seems to be created as a mdadm software raid. Calling mdadm --examine with the different partitions seems to affirm that. I think the only partition I am interested in, is /dev/sdc4 (because it is the largest). But nevertheless I called mdadm --examine with every partition. root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc1 /dev/sdc1: Magic : a92b4efc Version : 00.90.00 UUID : 5626a2d8:070ad992:ef1c8d24:cd8e13e4 Creation Time : Wed Feb 20 00:57:49 2002 Raid Level : raid1 Used Dev Size : 2939776 (2.80 GiB 3.01 GB) Array Size : 2939776 (2.80 GiB 3.01 GB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 1 Update Time : Sun Nov 21 11:05:27 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 4c90bc55 - correct Events : 16682 Number Major Minor RaidDevice State this 0 8 1 0 active sync /dev/sda1 0 0 8 1 0 active sync /dev/sda1 1 1 0 0 1 faulty removed root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc2 /dev/sdc2: Magic : a92b4efc Version : 00.90.00 UUID : 9734b3ee:2d5af206:05fe3413:585f7f26 Creation Time : Wed Feb 20 00:57:54 2002 Raid Level : raid1 Used Dev Size : 104320 (101.89 MiB 106.82 MB) Array Size : 104320 (101.89 MiB 106.82 MB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 2 Update Time : Wed Oct 27 20:19:08 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 55560b40 - correct Events : 9884 Number Major Minor RaidDevice State this 0 8 2 0 active sync /dev/sda2 0 0 8 2 0 active sync /dev/sda2 1 1 0 0 1 faulty removed root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc3 /dev/sdc3: Magic : a92b4efc Version : 00.90.00 UUID : 08f30b4f:91cca15d:2332bfef:48e67824 Creation Time : Wed Feb 20 00:57:54 2002 Raid Level : raid1 Used Dev Size : 987904 (964.91 MiB 1011.61 MB) Array Size : 987904 (964.91 MiB 1011.61 MB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 3 Update Time : Sun Nov 21 11:05:27 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 39717874 - correct Events : 73678 Number Major Minor RaidDevice State this 0 8 3 0 active sync 0 0 8 3 0 active sync 1 1 0 0 1 faulty removed root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc4 /dev/sdc4: Magic : a92b4efc Version : 00.90.00 UUID : febb75ca:e9d1ce18:f14cc006:f759419a Creation Time : Wed Feb 20 00:57:55 2002 Raid Level : raid1 Used Dev Size : 728515520 (694.77 GiB 746.00 GB) Array Size : 728515520 (694.77 GiB 746.00 GB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 4 Update Time : Sun Nov 21 11:05:27 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 2f36a392 - correct Events : 519320 Number Major Minor RaidDevice State this 0 8 4 0 active sync 0 0 8 4 0 active sync 1 1 0 0 1 faulty removed If I read the output correctly everything was removed, because it was faulty. Is there ANY way to see the contents of the largest partition? Or seeing somehow which files are broken? I see that everything is raid1 which is only mirroring, so this should be a normal partition. I am anxious to do anything with mdadm, in fear that I destroy the data on the hard disk. I would be very thankful for any help.

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• Generating strongly biased radom numbers for tests

  - by nobody

  I want to run tests with randomized inputs and need to generate 'sensible' random numbers, that is, numbers that match good enough to pass the tested function's preconditions, but hopefully wreak havoc deeper inside its code. math.random() (I'm using Lua) produces uniformly distributed random numbers. Scaling these up will give far more big numbers than small numbers, and there will be very few integers. I would like to skew the random numbers (or generate new ones using the old function as a randomness source) in a way that strongly favors 'simple' numbers, but will still cover the whole range, I.e. extending up to positive/negative infinity (or ±1e309 for double). This means: numbers up to, say, ten should be most common, integers should be more common than fractions, numbers ending in 0.5 should be the most common fractions, followed by 0.25 and 0.75; then 0.125, and so on. A different description: Fix a base probability x such that probabilities will sum to one and define the probability of a number n as xk where k is the generation in which n is constructed as a surreal number1. That assigns x to 0, x2 to -1 and +1, x3 to -2, -1/2, +1/2 and +2, and so on. This gives a nice description of something close to what I want (it skews a bit too much), but is near-unusable for computing random numbers. The resulting distribution is nowhere continuous (it's fractal!), I'm not sure how to determine the base probability x (I think for infinite precision it would be zero), and computing numbers based on this by iteration is awfully slow (spending near-infinite time to construct large numbers). Does anyone know of a simple approximation that, given a uniformly distributed randomness source, produces random numbers very roughly distributed as described above? I would like to run thousands of randomized tests, quantity/speed is more important than quality. Still, better numbers mean less inputs get rejected. Lua has a JIT, so performance can't be reasonably predicted. Jumps based on randomness will break every prediction, and many calls to math.random() will be slow, too. This means a closed formula will be better than an iterative or recursive one. 1 Wikipedia has an article on surreal numbers, with a nice picture. A surreal number is a pair of two surreal numbers, i.e. x := {n|m}, and its value is the number in the middle of the pair, i.e. (for finite numbers) {n|m} = (n+m)/2 (as rational). If one side of the pair is empty, that's interpreted as increment (or decrement, if right is empty) by one. If both sides are empty, that's zero. Initially, there are no numbers, so the only number one can build is 0 := { | }. In generation two one can build numbers {0| } =: 1 and { |0} =: -1, in three we get {1| } =: 2, {|1} =: -2, {0|1} =: 1/2 and {-1|0} =: -1/2 (plus some more complex representations of known numbers, e.g. {-1|1} ? 0). Note that e.g. 1/3 is never generated by finite numbers because it is an infinite fraction – the same goes for floats, 1/3 is never represented exactly.

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• How to prevent DIVs from sliding over each other

  - by Haghpanah

  I’m going to use DIV-based layout instead of table-based to reduce amount of markups and speed up page loading, however I’ve found it too much tricky as I’m not CSS guru. I use following CSS class to simulate rows of a table containing one column for label and one for textbox. .FormItem { margin-left: auto; margin-right: auto; width: 604px; min-height: 36px; } .ItemLabel { float: left; width: 120px; padding: 3px 1px 1px 1px; text-align: right; } .ItemTextBox { float: right; width: 480px; padding: 1px 1px 1px 1px; text-align: left; } , <div class="FormItem"> <div class="ItemLabel"> <asp:Label ID="lblName" runat="server" Text="Name :"></asp:Label> </div> <div class="ItemTextBox"> <asp:TextBox ID="txtName" runat="server"></asp:TextBox> <p><span>User Name</span></p> </div> </div> <div class="FormItem"> <div class="ItemLabel"> <asp:Label ID="lblComments" runat="server" Text="Comments :"></asp:Label> </div> <div class="ItemTextBox"> <asp:TextBox ID="txtComments" runat="server"></asp:TextBox> <p><span>(optional)Comments</span></p> </div> </div> These styles work fine if the height of ItemData DIVs are less than or equal to FormItem DIVs min-height. If ItemData DIVs height gets more than FormItem height then ItemText DIVs start sliding over FormItem DIVs to and ItemText and ItemData are no longer aligned. For example the following markups… <div class="FormItem"> <div class="ItemLabel"> <asp:Label ID="lblName" runat="server" Text="Name :"></asp:Label> </div> <div class="ItemTextBox"> <asp:TextBox ID="txtName" runat="server"></asp:TextBox> <p><span>User Name</span></p> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p> </div> </div> <div class="FormLabel"> <div class="ItemText"> <asp:Label ID="lblComments" runat="server" Text="Comments :"></asp:Label> </div> <div class="ItemTextBox"> <asp:TextBox ID="txtComments" runat="server"></asp:TextBox> <p><span>(optional)Comments</span></p> </div> </div> I've tried several CSS attributes such as; position, float, clear… but I can not correct the problem. I’ll be appreciated for any help.

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• Get backreferences values and modificate these values

  - by roasted

  Could you please explain why im not able to get values of backreferences from a matched regex result and apply it some modification before effective replacement? The expected result is replacing for example string ".coord('X','Y')" by "X * Y". But if X to some value, divide this value by 2 and then use this new value in replacement. Here the code im currently testing: See /*>>1<<*/ & /*>>2<<*/ & /*>>3<<*/, this is where im stuck! I would like to be able to apply modification on backrefrences before replacement depending of backreferences values. Difference between /*>>2<<*/ & /*>>3<<*/ is just the self call anonymous function param The method /*>>2<<*/ is the expected working solution as i can understand it. But strangely, the replacement is not working correctly, replacing by alias $1 * $2 and not by value...? You can test the jsfiddle //string to test ".coord('125','255')" //array of regex pattern and replacement //just one for the example //for this example, pattern matching alphanumerics is not necessary (only decimal in coord) but keep it as it var regexes = [ //FORMAT is array of [PATTERN,REPLACEMENT] /*.coord("X","Y")*/ [/\.coord\(['"]([\w]+)['"],['"]?([\w:\.\\]+)['"]?\)/g, '$1 * $2'] ]; function testReg(inputText, $output) { //using regex for (var i = 0; i < regexes.length; i++) { /*==>**1**/ //this one works as usual but dont let me get backreferences values $output.val(inputText.replace(regexes[i][0], regexes[i][2])); /*==>**2**/ //this one should works as i understand it $output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) { $1 = checkReplace(match, $1, $2, $3, $4); //here want using $1 modified value in replacement return regexes[i][3]; })); /*==>**3**/ //this one is just a test by self call anonymous function $output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) { $1 = checkReplace(match, $1, $2, $3, $4); //here want using $1 modified value in replacement return regexes[i][4]; }())); inputText = $output.val(); } } function checkReplace(match, $1, $2, $3, $4) { console.log(match + ':::' + $1 + ':::' + $2 + ':::' + $3 + ':::' + $4); //HERE i should be able if lets say $1 > 200 divide it by 2 //then returning $1 value if($1 > 200) $1 = parseInt($1 / 2); return $1; }? Sure I'm missing something, but cannot get it! Thanks for your help, regards. EDIT WORKING METHOD: Finally get it, as mentionned by Eric: The key thing is that the function returns the literal text to substitute, not a string which is parsed for backreferences.?? JSFIDDLE So complete working code: (please note as pattern replacement will change for each matched pattern and optimisation of speed code is not an issue here, i will keep it like that) $('#btn').click(function() { testReg($('#input').val(), $('#output')); }); //array of regex pattern and replacement //just one for the example var regexes = [ //FORMAT is array of [PATTERN,REPLACEMENT] /*.coord("X","Y")*/ [/\.coord\(['"]([\w]+)['"],['"]?([\w:\.\\]+)['"]?\)/g, '$1 * $2'] ]; function testReg(inputText, $output) { //using regex for (var i = 0; i < regexes.length; i++) { $output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) { var checkedValues = checkReplace(match, $1, $2, $3, $4); $1 = checkedValues[0]; $2 = checkedValues[1]; regexes[i][1] = regexes[i][1].replace('$1', $1).replace('$2', $2); return regexes[i][1]; })); inputText = $output.val(); } } function checkReplace(match, $1, $2, $3, $4) { console.log(match + ':::' + $1 + ':::' + $2 + ':::' + $3 + ':::' + $4); if ($1 > 200) $1 = parseInt($1 / 2); if ($2 > 200) $2 = parseInt($2 / 2); return [$1,$2]; }

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• Having trouble with multiple Jquery libraries

  - by user3716971

  I've seen the posts about the no conflict but I'm not very code savvy and can't figure it out alone. I'm having trouble making two libraries work together. At the top I have the 1.9.1 library which controls a news ticker, and a carousel. Near the bottom there is a library 1.6.1, which controls a Dribbble feed. If I remove 1.6.1 everything but the dribbble feed works, and if I remove the 1.9.1 the dribbble feed is the only thing that works. I uploaded the website for you guys to check out. If you could edit my code to make it work that would be amazing, I don't have much knowledge of jquery. This version has a working dribbble feed at the very bottom http://michaelcullenbenson.com/MichaelCullenBenson.com/index.html and this version has a broken feed and everything else works. http://michaelcullenbenson.com/MichaelCullenBenson.com/index2.html Help would be AMAZING as the dribbble feed is the last element I'm trying to finish on my homepage and I'll be able to move on. <script type="text/javascript" src="js/jquery-1.9.1.min.js"></script> <script type="text/javascript" src="js/jquery.innerfade.js"></script> <script type="text/javascript"> $(document).ready( function(){ $('#news').innerfade({ animationtype: 'slide', speed: 600, timeout: 6000, type: 'random', containerheight: '1em' }); }); </script> <!-- Include all compiled plugins (below), or include individual files as needed --> <script src="utilcarousel-files/utilcarousel/jquery.utilcarousel.min.js"></script> <script src="utilcarousel-files/magnific-popup/jquery.magnific-popup.js"></script> <script src="js/responsive-nav.js"></script> <script> $(function() { $('#fullwidth').utilCarousel({ breakPoints : [[600, 1], [800, 2], [1000, 3], [1300, 4],], mouseWheel : false, rewind : true, autoPlay : true, pagination : false }); $('#fullwidth2').utilCarousel({ breakPoints : [[600, 1], [800, 2], [1000, 3], [1300, 4],], mouseWheel : false, rewind : true, autoPlay : true, pagination : false }); }); </script> <script> $(document).ready(function() { var movementStrength = 25; var height = movementStrength / $(window).height(); var width = movementStrength / $(window).width(); $("#aboutarea").mousemove(function(e){ var pageX = e.pageX - ($(window).width() / 2); var pageY = e.pageY - ($(window).height() / 2); var newvalueX = width * pageX * -1 - 25; var newvalueY = height * pageY * -1 - 50; $('#aboutarea').css("background-position", newvalueX+"px "+newvalueY+"px"); }); }); </script> <script src="//ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js" type="text/javascript"></script> <script type="text/javascript" src="dribbble.js"></script> <script type="text/javascript"> $(function () { $('#user').dribbble({ player: 'MCBDesign', total: 1 }); }); </script>

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• How to Upgrade Your Netbook to Windows 7 Home Premium

  - by Matthew Guay

  Would you like more features and flash in Windows on your netbook?  Here’s how you can easily upgrade your netbook to Windows 7 Home Premium the easy way. Most new netbooks today ship with Windows 7 Starter, which is the cheapest edition of Windows 7.  It is fine for many computing tasks, and will run all your favorite programs great, but it lacks many customization, multimedia, and business features found in higher editions.  Here we’ll show you how you can quickly upgrade your netbook to more full-featured edition of Windows 7 using Windows Anytime Upgrade.  Also, if you want to upgrade your laptop or desktop to another edition of Windows 7, say Professional, you can follow these same steps to upgrade it, too. Please note: This is only for computers already running Windows 7.  If your netbook is running XP or Vista, you will have to run a traditional upgrade to install Windows 7. Upgrade Advisor First, let’s make sure your netbook can support the extra features, such as Aero Glass, in Windows 7 Home Premium.  Most modern netbooks that ship with Windows 7 Starter can run the advanced features in Windows 7 Home Premium, but let’s check just in case.  Download the Windows 7 Upgrade Advisor (link below), and install as normal. Once it’s installed, run it and click Start Check.   Make sure you’re connected to the internet before you run the check, or otherwise you may see this error message.  If you see it, click Ok and then connect to the internet and start the check again. It will now scan all of your programs and hardware to make sure they’re compatible with Windows 7.  Since you’re already running Windows 7 Starter, it will also tell you if your computer will support the features in other editions of Windows 7. After a few moments, the Upgrade Advisor will show you want it found.  Here we see that our netbook, a Samsung N150, can be upgraded to Windows 7 Home Premium, Professional, or Ultimate. We also see that we had one issue, but this was because a driver we had installed was not recognized.  Click “See all system requirements” to see what your netbook can do with the new edition. This shows you which of the requirements, including support for Windows Aero, your netbook meets.  Here our netbook supports Aero, so we’re ready to go upgrade. For more, check out our article on how to make sure your computer can run Windows 7 with Upgrade Advisor. Upgrade with Anytime Upgrade Now, we’re ready to upgrade our netbook to Windows 7 Home Premium.  Enter “Anytime Upgrade” in the Start menu search,and select Windows Anytime Upgrade. Windows Anytime Upgrade lets you upgrade using product key you already have or one you purchase during the upgrade process.  And, it installs without any downloads or Windows disks, so it works great even for netbooks without DVD drives. Anytime Upgrades are cheaper than a standard upgrade, and for a limited time, select retailers in the US are offering Anytime Upgrades to Windows 7 Home Premium for only $49.99 if purchased with a new netbook.  If you already have a netbook running Windows 7 Starter, you can either purchase an Anytime Upgrade package at a retail store or purchase a key online during the upgrade process for $79.95.  Or, if you have a standard Windows 7 product key (full or upgrade), you can use it in Anytime upgrade.  This is especially nice if you can purchase Windows 7 cheaper through your school, university, or office. Purchase an upgrade online To purchase an upgrade online, click “Go online to choose the edition of Windows 7 that’s best for you”.   Here you can see a comparison of the features of each edition of Windows 7.  Note that you can upgrade to either Home Premium, Professional, or Ultimate.  We chose home Premium because it has most of the features that home users want, including Media Center and Aero Glass effects.  Also note that the price of each upgrade is cheaper than the respective upgrade from Windows XP or Vista.  Click buy under the edition you want.   Enter your billing information, then your payment information.  Once you confirm your purchase, you will directly be taken to the Upgrade screen.  Make sure to save your receipt, as you will need the product key if you ever need to reinstall Windows on your computer. Upgrade with an existing product key If you purchased an Anytime Upgrade kit from a retailer, or already have a Full or Upgrade key for another edition of Windows 7, choose “Enter an upgrade key”. Enter your product key, and click Next.  If you purchased an Anytime Upgrade kit, the product key will be located on the inside of the case on a yellow sticker. The key will be verified as a valid key, and Anytime Upgrade will automatically choose the correct edition of Windows 7 based on your product key.  Click Next when this is finished. Continuing the Upgrade process Whether you entered a key or purchased a key online, the process is the same from here on.  Click “I accept” to accept the license agreement. Now, you’re ready to install your upgrade.  Make sure to save all open files and close any programs, and then click Upgrade. The upgrade only takes about 10 minutes in our experience but your mileage may vary.  Any available Microsoft updates, including ones for Office, Security Essentials, and other products, will be installed before the upgrade takes place. After a couple minutes, your computer will automatically reboot and finish the installation.  It will then reboot once more, and your computer will be ready to use!  Welcome to your new edition of Windows 7! Here’s a before and after shot of our desktop.  When you do an Anytime Upgrade, all of your programs, files, and settings will be just as they were before you upgraded.  The only change we noticed was that our pinned taskbar icons were slightly rearranged to the default order of Internet Explorer, Explorer, and Media Player.  Here’s a shot of our desktop before the upgrade.  Notice that all of our pinned programs and desktop icons are still there, as well as our taskbar customization (we are using small icons on the taskbar instead of the default large icons). Before, with the Windows 7 Starter background and the Aero Basic theme: And after, with Aero Glass and the more colorful default Windows 7 background.   All of the features of Windows 7 Home Premium are now ready to use.  The Aero theme was activate by default, but you can now customize your netbook theme, background, and more with the Personalization pane.  To open it, right-click on your desktop and select Personalize. You can also now use Windows Media Center, and can play-back DVD movies using an external drive. One of our favorite tools, the Snipping Tool, is also now available for easy screenshots and clips. Activating you new edition of Windows 7 You will still need to activate your new edition of Windows 7.  To do this right away, open the start menu, right-click on Computer, and select Properties.   Scroll to the bottom, and click “Activate Windows Now”. Make sure you’re connected to the internet, and then select “Activate Windows online now”. Activation may take a few minutes, depending on your internet connection speed. When it is done, the Activation wizard will let you know that Windows is activated and genuine.  Your upgrade is all finished! Conclusion Windows Anytime Upgrade makes it easy, and somewhat cheaper, to upgrade to another edition of Windows 7.  It’s useful for desktop and laptop owners who want to upgrade to Professional or Ultimate, but many more netbook owners will want to upgrade from Starter to Home Premium or another edition.  Links Download the Windows 7 Upgrade Advisor Windows Team Blog: Anytime Upgrade Special with new PC purchase Similar Articles Productive Geek Tips How To Upgrade from Vista to Windows 7 Home Premium EditionAnother Blog You Should Subscribe ToMysticgeek Blog: Turn Vista Home Premium Into Ultimate (Part 3) – Shadow CopyUpgrade Ubuntu from Breezy to DapperHow to Upgrade the Windows 7 RC to RTM (Final Release) TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Get Your Delicious Bookmarks In Firefox’s Awesome Bar Manage Photos Across Different Social Sites With Dropico Test Drive Windows 7 Online Download Wallpapers From National Geographic Site Spyware Blaster v4.3 Yes, it’s Patch Tuesday

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